The present invention relates to a printing press for performing printing on a lenticular lens sheet and a printing method.
As shown in FIG. 45A, a lenticular lens sheet 1 is formed by arranging a plurality of long lenses each having a semicircular section in stripes at a pitch of 0.1 mm to 0.7 mm. As shown in FIG. 45B, pairs of pattern portions A1/B1, A2/B2, . . . , for right and left eyes are printed on the reverse surface of the lenticular lens sheet 1 at an interval of ½ the lens width. An observer views different images with depth on one lenticular lens sheet 1 in accordance with his/her observation direction. This realizes stereopsis by so-called optical illusion.
There are not only the above-described lenticules having a pattern printed on the lenticular lens sheet 1 to provide a view of a stereoscopic image but also lenticules that combine a plurality of totally different patterns to change the image depending on the viewing angle and lenticules that combine a plurality of gradually changing patterns to produce a moving image.
Such an effect of lenticules can be obtained by accurately positioning the lenticular lens sheet 1 formed by arranging a number of long lenses at a specific pitch and a pattern formed by arranging a number of long patterns at a specific pitch. Even in a very small amount, a positional shift between them makes it impossible to obtain the effect. For this reason, alignment between the lenticular lens sheet 1 and the pattern to be printed is very important.
Japanese Patent Laid-Open No. 2007-152818 (literature 1) proposes, as a register adjustment device of a printing press for performing printing on the lenticular lens sheet 1, a device that adjusts the position of a plate with respect to the lenticular lens sheet 1 using a register adjustment mechanism. In the technique of literature 1, when the operator inputs a misregistration amount to the control console, the register adjustment mechanisms of all printing units operate based on the misregistration amount and perform register adjustment of the plate cylinders.
In the technique of literature 1, however, the operator needs to visually confirm the misregistration amount of the printed lenticular lens sheet 1, determine the actual register adjustment amount based on the misregistration amount, and perform printing again after that. For this reason, a lot of rejected sheets are produced. As a result, the advantages of directly printing the pattern on the lenticular lens sheet 1, lead time shortening and large cost reduction, are lost.